Support for main filter and prefilter



Aug. 25, 19%) W. L. SMYFEH SUPPORT FOR MAIN FILTER AND PREFILTER FiledNov. 27, 1968 1N VENTOR. WA wva LSM/T'H.

United States Patent Office SUPPORT FOR MAIN FILTER AND PREFILTER WayneL. Smith, Bradford Woods, Pa., assignor to Mine Safety AppliancesCompany, Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 27,1968, Ser. No. 779,436 Int. Cl. B01d 50/00 US. Cl. 55-484 7 ClaimsABSTRACT OF THE DISCLOSURE A rectangular frame for holding a main filterhas a plurality of rods detachably connected to its sidewalls andextending out of one end of it. Close to one side of each rod outside ofthe frame is the body of a bracket, which has a pair of spaced flangesprojecting laterally from one side and provided with aligned holesslidingly receiving the rod. Each pair of bracket flanges is positionedto receive an edge of a prefilter between them while the inner flangeengages the adjoining end of a main filter in the frame. Nuts screwedonto the outer ends of the rods engage the outer bracket flanges.

Filtering apparatus often includes a frame, in which a filter isremovably mounted. In many cases several frames may be joined side byside, or a single large frame may be provided with compartments, toprovide for a bank of filters. In order to hold the filters in theframes and also to hold prefilters against the inlet ends of the mainfilters, various means have been proposed and used. One scheme is shownin Pat. No. 3,250,063, in which spring strips are used for that purpose.

It is among the objects of this invention to provide apparatus forsupporting a rectangular main filter and a prefilter, which is simple inconstruction, which is adjustable, which can be quickly applied, andwhich can be used with single filters or with banks of filters.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a side view of a completeunit;

FIG. 2 is a fragmentary front view;

FIG. 3 is a fragmentary rear view;

FIG. 4 is an enlarged fragmentary plan view; and

FIG. 5 is a rear view of one of the brackets alone.

Referring to the drawings, a sheet metal rectangular frame 1 has alength or depth that is less than the depth of a main filter 2 that ithouses. The filter is inserted from the inlet end of the frame andpushed forward until it seats against an integral flange 3 (FIG. 2)projecting inwardly from the front or outlet end of the frame. A seal isformed between the flange and the adjoining filter so that air cannotbypass the filter. The filter projects from the back of the frame. Thefilter is spaced a short distance from the sides of the frame byindentations 4 in the side walls of the frame.

In order to hold the filter in the frame and tightly against the frontflange, a plurality of retaining members are provided. Each of thesemembers is formed from a rod 6, a nut 7 and a bracket 8. In some casesonly two retaining members may be used, one on each of two oppositesides of the frame. In other cases there may be a retaining member ateach side of the frame, or two or all four sides of the frame may beprovided with two retaining members each. Each rod has an inner end thatextends only a short distance into the frame adjacent a side wallthereof, to which the rod is detachably connected. A very convenient wayof connecting the rods to the sides of the frame is to provide the sideswith openings 9 near their rear edges as shown in FIGS. 1 and 4, and toform the inner ends of the rods into the 3,525,200 Patented Aug. 25,1970 shape of hooks 10 that hook into those openings. The space betweenthe filter and the sides of the frame makes it easy to insert the rodsafter the filter has been placed in the frame. With the filter in place,the rods extend backward behind it several inches and have screwthreadedrear end portions.

Slidably mounted on each rod behind the frame is a bracket 8, each ofwhich has a flat body 12 disposed close to the side of the rod andextending lengthwise of it. Projecting laterally from the opposite endsof this body are two generally parallel flanges 13 and 14, provided withaligned holes 15, through which the rod extends. Threaded on the outerend of the rod is wing nut 7 that engages the outer flange 14. Bytightening this nut, the bracket can be slid inwardly along the rod. Thedistance between the bracket flanges is such as to snugly receive anedge of a prefilter 17 between them. This prefilter is positionedagainst the inlet end of the main filter and removes large foreignparticles from the gas flowing through it before they can reach the mainfilter. By turning the wing nuts inwardly on the rods around the frame,the brackets will hold the prefilter securely against the main filterwhile the inner bracket flanges 13, which overlap the rear edge of themain filter, press that filter forward against the front flange 3 of themetal frame. Preferably, the free ends of the inner flanges of thebrackets are turned toward the main filter as shown in FIG. 4, so thatthey hook over its edge and thereby help to prevent the brackets fromaccidentally swinging laterally away from the filters.

When the banks of filters are used, some of the rods can supportbrackets that hold two adjoining pairs of main filters and prefilters.To do this, another pair of spaced flanges 20 and 21 project from theside of a bracket body opposite the rod on which it is mounted. Thesecond pair of flanges serve the same purpose as the first pair, butwith an adjoining main filter 22 and prefilter 23 such as indicated inbroken lines in FIG. 4. The body of the bracket can be made in one pieceor from two flat webs 24 that are held face to face, such as by weldingor riveting, each web being integral with the flange at its oppositeends. However, since the filters are not always arranged in banks sothat two sets of flanges are not always needed, it may be desirable todetachably connect the two webs to permit one web and its flanges to beomitted. This can be done conveniently by providing one of the webs withopenings, such as parallel slots 26, and providing the other withstruck-out tongues 27 that extend through the slots. It is best toprovide the web that is next to the rod with the tongues so that theyextend away from the rod and do not interfere with it. By inclining thetongues from that Web toward the inner flanges of the bracket thetongues will hold the two webs together because the pressure of flange20 against filter 22 will prevent the slotted web from moving inwardlyrelative to the other web and sliding off the tongues.

The retaining members disclosed herein are simple and inexpensive inconstruction and permit a prefilter to be clamped tightly against a mainfilter and to hold both firmly in a frame. If a prefilter is not used,the brackets still press the main filter tightly against the frontflange of the frame. When only one filter unit is used, then only singlebrackets with flanges 13 and 14 are necessary, but when two units areplaced side by side, double brackets are employed so that flanges 20 and21 will be available. The conversion from single to double bracketsrequires only a moment.

I claim:

1. Apparatus for supporting a rectangular main filter and holding arectangular prefilter against its inlet end, said apparatus comprising arectangular frame adapted to receive the main filter and provided at oneend with an inwardly projecting flange for overlapping the marginal areaof the outlet end of the main filter, a plurality of rods having innerends inside the frame and detachably connected to different side wallsthereof, the rods projecting from the end of the frame opposite theflanged end and having screw threaded outer end portions, brackets withbodies close to the sides of the rods and extending lengthwise thereof,each bracket also having a pair of spaced flanges projecting laterallyfrom the rod side of its body and provided with aligned holes slidinglyreceiving a rod, each pair of bracket flanges receiving an edge of theprefilter between them, and nuts screwed onto the outer ends of the rodsand engaging the outer bracket flanges, whereby the inner bracketflanges can be pressed against the inlet end of the main filter to holdthat filter in the frame.

2. Apparatus according to claim 1, in which the side walls of said frameare provided with openings, and the inner ends of said rods are hookshape and hooked into said openings.

3. Apparatus according to claim 1, in which another pair of spacedflanges project from the side of each bracket body opposite thefirst-mentioned pair for receiving the edge of another prefilter.

4. Apparatus according to claim 1, in which the free ends of said innerbracket flanges are bent away from the outer bracket flanges.

5. Apparatus according to claim 3, in which said body is formed from twoflat webs and means holding them face to face, and each pair of saidflanges project from a different one of said webs.

6. Apparatus according to claim 3, in which each of said bracket bodiesis formed from two flat webs in face to face engagement with each other,one of said webs being provided with an opening through it, and theother web having a struck-out tongue extending through said opening,each pair of said flanges projecting from a different one of said webs.

7. Apparatus according to claim 6, in which said tongue projects fromsaid first-mentioned web and is inclined toward the inner end of thatweb.

References Cited UNITED STATES PATENTS 1,483,379 2/1924 Reed 555043,350,862 11/1967 Nutting 5548f4 3,385,034 5/1968 Farr 55503 FRANK W.LUTTER, Primary Examiner B. NOZICK, Assitsant Examiner U.S. Cl. X.R.

